Дисертації з теми "Solar engines"
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1
Gaitan, Carlos. "Rural electrification in Bolivia through solar powered Stirling engines." Thesis, KTH, Energiteknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-148079.
Анотація:
This study focuses on the rural areas of Bolivia. The village investigated is assumed to have 70 households and one school. Electrical supply will be covered with the help of solar powered Stirling engines. A Stirling engine is an engine with an external heat source, which could be fuel or biomass for example. The model calculates the electrical demand for two different cases. One low level demand and one high level demand. By studying the total electrical demand of the village, the model can calculate a sizing for the Stirling system. However, for the sizing to be more accurate, more research needs to be done with regards to the demand of the village and the incoming parameters of the model.Den här studien fokuserar på landsbygden i Bolivia. En by som antas ha 70 hushåll och en skola är det som ligger till grund för studien. Byn ska försörjas med el med hjälp av soldrivna Stirling motorer. En Stirling motor är en motor som drivs med en extern värmekälla. Denna värmekälla kan vara exempelvis biomassa eller annan bränsle. Modellen som tas fram i projektet beräknar elektricitetsbehovet för byn för två nivåer, ett lågt elbehov och ett högt elbehov. Genom att studera det totala elbehovet över dagen kan modellen beräkna fram en storlek för Stirling systemet. För att ge mer noggranna svar, krävs dock att forskning utförs i byn som ska försörjas. Dessutom krävs en mer noggrann information om de ingående parametrarna i modellen.
2
Clark, David Anthony. "High performance heat engines for solar and biomass applications." Thesis, Queensland University of Technology, 1993. https://eprints.qut.edu.au/226903/1/T%28BE%26E%29%20375_Clark_1993.pdf.
Анотація:
Generation systems which are fuelled by renewable energy sources, such as solar
and biomass, are the environmentally-preferred option for the production
of electricity and heat. This study examines the technical and economic feasibility
of small-scale (less than 1 MW) renewable generation systems based on
a steam-driven engine. Specifically, the study investigates the thermodynamic
and mechanical design of the engine.
The theory of engine operation is presented in Chapter 3 of this thesis. A
computor model of the engine was used to predict the performance of different
engine configurations. The model, although thermodynamically correct, did not
consider the effect of valve dynamics on engine performance.
Appendix 1 contains sample engine analyses based on the theory of engine
operation. From the calculations, it can be seen that valve dynamics has a
significant effect on engine throughput, efficiency and operating pressure. For a
given engine configuration with set mass flow and thermal input, valve dynamics
alters inlet valve timing and delays closure. This causes a reduction in efficiency
and peak operating pressure.
The suitability of ceramics or hardened-tool steels as steam inlet valves is discussed
in Chapter 4. A magnesia partially-stabilised zirconia ball was tested
for several hours in a single-cylinder engine.
A purpose-built engine test facility was used to obtain data on the variation
in the cylinder pressure throughout an engine cycle. The experimental work
highlighted several areas associated with the design of the inlet valve and steam
supply system where improvements could be made. During tests, the engine
was able to achieve conversion efficiencies greater than 20% heat-in to shaft-out.
A solar or biomass-fired generation facility can be operated and maintained by
persons with basic technical skills and requires less maintenance and attention
than diesel generators. Based on the cunent engine efficiency and the eff ectiveness
of other system c_omponents, the expected overall economics of engine-based power generation compares favourably with the traditional diesel-based
systems currently used in remote areas of Australia and overseas.
3
Tegeder, Troy. "Development of an efficient solar powered unmanned aerial vehicle with an onboard solar tracker /." Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd1723.pdf.
4
Gohary, Mohamed Morsy Abdel Meguid Salama el. "Diesel engines and solar energy for electric and cooling applications." [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=973168242.
5
Kheder, Abdul-Sameei Yaseen. "Starting high inertia, high friction loads from limited power sources." Diss., The University of Arizona, 1988. http://hdl.handle.net/10150/184455.
Анотація:
At starting, electrical motors require large power and current. This may not be a problem in a large electrical system but it may be very severe for a limited power source like a solar array. If a direct approach is taken the array rating must be 5-6 times the motor rating in order to start the motor and its high inertia high friction load. Batteries have been used to store energy and supply that energy for starting. Batteries need maintenance and their low efficiency is a problem too. In this study a new type of controller has been suggested and developed for the use with D.C. motors. Computer simulation showed promising results. The controller uses the array power, which is equal to the rated power of the motor, for starting and for running condition. Experimental results showed that the theoretical results are applicable.
6
Howard, Dustin F. "Modeling, simulation, and analysis of grid connected dish-stirling solar power plants." Thesis, Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34832.
Анотація:
The percentage of renewable energy within the global electric power generation portfolio is expected to increase rapidly over the next few decades due to increasing concerns about climate change, fossil fuel costs, and energy security. Solar thermal energy, also known as concentrating solar power (CSP), is emerging as an important solution to new demands for clean, renewable electricity generation. Dish-Stirling (DS) technology, a form of CSP, is a relatively new player in the renewable energy market, although research in the technology has been ongoing now for nearly thirty years. The first large plant utilizing DS technology, rated at 1.5 MW, came online in January 2010 in Peoria, AZ, and plants rated for several hundred MW are in the planning stages. Increasing capacity of this technology within the utility grid requires extensive dynamic simulation studies to ensure that the power system maintains its safety and reliability in spite of the technological challenges that DS technology presents, particularly related to the intermittency of the energy source and its use of a non-conventional asynchronous generator. The research presented in this thesis attempts to fill in the gaps between the well established research on Stirling engines in the world of thermodynamics and the use of DS systems in electric power system applications, a topic which has received scant attention in publications since the emergence of this technology.
DS technology uses a paraboloidal shaped dish of mirrors to concentrate sunlight to a single point. The high temperatures achieved at the focal point of the mirrors is used as a heat source for the Stirling engine, which is a closed-cycle, external heat engine. Invented by the Scottish clergyman Robert Stirling in 1816, the Stirling engine is capable of high efficiency and releases no emissions, making it highly compatible with concentrated solar energy. The Stirling engine turns a squirrel-cage induction generator, where electricity is delivered through underground cables from thousands of independent, autonomous 10-25 kW rated DS units in a large solar farm.
A dynamic model of the DS system is presented in this thesis, including models of the Stirling engine working gas and mechanical dynamics. Custom FORTRAN code is written to model the Stirling engine dynamics within PSCAD/EMTDC. The Stirling engine and various other components of the DS system are incorporated into an electrical network, including first a single-machine, infinite bus network, and then a larger 12-bus network including conventional generators, loads, and transmission lines. An analysis of the DS control systems is presented, and simulation results are provided to demonstrate the system's steady state and dynamic behavior within these electric power networks. Potential grid interconnection requirements are discussed, including issues with power factor correction and low voltage ride-through, and simulation results are provided to illustrate the dish-Stirling system's capability for meeting such requirements.
7
Dentello, Rodrigo Orefise. "Estudo de geração de energia elétrica em motores stirling acionados por biogás e/ou energia solar /." Guaratinguetá, 2017. http://hdl.handle.net/11449/151835.
Анотація:
Orientador: Jose Luz SilveiraCoorientadora: Eliana Vieira Canettieri
Coorientador: Antonio Wagner Forti
Banca: Nestor proenza Pérez
Banca: Ederaldo Godoy Junior
Resumo: O motor Stirling é um motor de combustão externa que opera com diferenças de temperaturas, produzindo trabalho mecânico e eletricidade. Esse tipo de motor opera em um ciclo fechado, que através do uso de uma fonte quente e uma fria, expande e comprime um fluido de trabalho (ar, hélio ou hidrogênio, dentre os mais comuns), fornecendo assim o movimento de um pistão. Pode operar com calor residual e também com a queima de qualquer tipo de combustível (gás natural, diesel, gasolina, etc). Essa tecnologia tem se destacado para o desenvolvimento de sistemas que operam com biocombustíveis (biogás e syngas) e com energias renováveis, como por exemplo, caso de uso de concentradores solares. Este trabalho tem como objetivo estudar as performances termodinâmica, econômica e ambiental de um sistema Stirling operando com sistema de alimentação a biogás e energia solar, aplicado para a geração de energia elétrica descentralizada. São realizados estudos dos aspectos termodinâmicos do ciclo Stirling, com foco no funcionamento e no trabalho do motor. São efetuadas análises técnicas do sistema operando com câmara de combustão a biogás e utilizando energia de concentrador solar parabólico. Em etapa final são analisados e comparados os aspectos econômicos e ambientais do sistema acionado por biogás e energia solar. Os resultados obtidos mostraram pela teoria de Schmidt uma eficiência do motor Stirling de 67%. Da análise econômica, fica evidente que um maior número de horas de operação corrobora ... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The Stirling engine is an external combustion engine that operates at varying temperatures, producing mechanical work or electricity. This type of engine operates in a closed cycle, which through the use of a hot and cold source expands and compresses a working fluid (air, helium or hydrogen, among the most common), thus providing the movement of a piston. It can operate with residual heat and also with the burning of any type of fuel (natural gas, diesel, gasoline, etc.). This technology has been outstanding for the development of hybrid systems that operate with biofuels (biogas and syngas) and with renewable energies, as for example, case of use of solar concentrators. This work aims to study the thermodynamic, economic and environmental performances of a Stirling system operating with a biogas and solar energy supply system, applied for the generation of decentralized electric energy. Studies are carried out on the thermodynamic aspects of the Stirling cycle, focusing on the operation and work of the engine. Technical analysis of the system is carried out using a biogas combustion chamber and using parabolic solar concentrator energy. In the final stage are analyzed and compared the economic and environmental aspects of the system activated by biogas and solar energy. The results showed that through the thermodynamic analysis by the Schmidt theory, a Stirling engine efficiency of 67% was obtained. From the economic analysis, it is evident that a greater number of hours of operation corroborates with economic viability. As for the environmental aspects, the ecological efficiency value of the Stirling engine operating biogas is 98.02%. In the case of the solar system using concentrator to power the Stirling engine, the ecological efficiency indicates is about 98%. It is concluded that the use of renewable sources, allow good levels of efficiency of electric power ... (Complete abstract click electronic access below)
Mestre
8
McHugh, Megan. "Solar Powered Stirling Engine." The University of Arizona, 2017. http://hdl.handle.net/10150/623462.
Анотація:
Sustainable Built Environments Senior Capstone ProjectThis paper provides a study on the configuration of Stirling engines and the effect using a solar dish as a heat source on efficiency. The Stirling engine was based on the MIT 2.670 design - a Gamma configuration, low temperature differential Stirling engine. Temperature and speed were measured for the base model Stirling engine to determine the initial efficiency. Modifications were planned to add a parabolic mirror as a solar dish and compare the efficiency to the initial design, however, the completed solar Stirling engine testing and data collection is to be performed in the following summer. The work performed by the engine was to be calculated using the Schmidt formula to then find the power output. Results from the completion of this study would indicate how the solar dish effects the power output of the Stirling engine.
9
Ghaem, Sigarchian Sara. "Modeling and Analysis of a Hybrid Solar-Dish Brayton Engine." Thesis, KTH, Kraft- och värmeteknologi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-104425.
10
Chen, Mingfei. "Computer simulation of Ringbom stirling engine with solar pond." Ohio University / OhioLINK, 1989. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1182285925.
11
Mabrouk, Mohamed Tahar. "Production optimale d’énergie pour une communauté à petite échelle : application à l’optimisation d’une centrale solaire hybride produisant électricité et chaleur." Thesis, Université de Lorraine, 2015. http://www.theses.fr/2015LORR0163/document.
Анотація:
Ce travail traite la modélisation et l'optimisation des centrales solaires thermodynamiques à concentration produisant de l'électricité pour l'électrification des zones rurales isolées et mal raccordées au réseau électrique. D’abord, un modèle optique et thermique détaillé des concentrateurs solaires cylindro-paraboliques est présenté permettant l'identification de capteurs existants et la création de corrélations qui peuvent être injectées dans un modèle plus global. Dans un second temps, un modèle original d'un stock de chaleur stratifié de type « lit de roche » est développé. Le nouveau modèle proposé permet de déterminer analytiquement le profil de température dans le stock à n'importe quel instant dans le cas d'une température d'entrée régulée. Ensuite, deux alternatives de bloc moteur sont modélisées : le moteur Stirling et le Cycle Organique de Rankine (ORC acronyme anglais pour Organic Rankine Cycle). Concernant le moteur Stirling, une revue critique des modèles existants a été effectuée. Certains de ces modèles ont été implémentés et complétés par des modèles originaux des pertes par fuite de matière et par effet navette. Le cycle organique de Rankine, lui, est modélisé par un modèle orientée vers l'optimisation. Enfin, une optimisation mono et multicritère d’une centrale solaire est effectuée. La configuration étudiée est équipée d’un stock de chaleur et d’une chaudière d’appoint. Elle est optimisée selon trois critères : le coût moyen actualisé de l'électricité (LCOE acronyme anglais pour Levelized Cost Of Electricity), le rendement énergétique de la centrale et la quantité de CO2 émise par Kilowatt heure d'électricité produiteThis work deals with the modelling and the optimization of thermodynamic solar power plants intended to supply electricity to isolated locations. Firstly, a state of the art of solar collectors is achieved and a model for parabolic trough collectors is proposed. This model is used for actual collectors identification. It is used also to propose correlations to be introduced in the whole system model. In a second time, a state of the art of energy storage technologies is conducted and an original model of a packed bed storage tank is proposed. This model gives an explicit solution of the temperature inside the tank without using a time step based numerical resolution. Two alternatives for the power block are given: Stirling engines and Organic Rankine Cycles. For Stirling engines, a critical review of existing models is performed. Some losses occurring in Stirling engines are not well documented in the literature as leakage losses at the power piston and displacer gap losses. Therefore, original models are proposed to estimate these losses. When compared to former models in the literature, the new model of the displacer gap losses demonstrates clearly that it is very important to use decoupled models with caution. Concerning the ORC, an optimization-oriented model is proposed. Finally, a mono and multi-objective optimization of a solar power plant is performed. The optimized system is composed of a solar field, a packed bed heat storage, a power block and an auxiliary fired heater. Objective functions used in this study are: the Levelized Cost of Electricity (LCOE), the energetic efficiency of the power plant and CO2 emission per kilowatt hour of electricity
12
PRADERE, GUILLAUME LOUIS. "PERFORMANCE SIMULATION OF A THERMOELECTRIC PLANT PREHEATING DIESEL ENGINE SYSTEM VIA SOLAR ENERGY." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2017. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=31824@1.
Анотація:
PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE EXCELENCIA ACADEMICA
Este trabalho tem por objetivo principal a avaliação de desempenho de um sistema piloto de preaquecimento dos motores da central termelétrica Gera Maranhão, via energia solar térmica, em Miranda do Norte, Maranhão, através de uma simulação numérica. Cinco subsistemas independentes, cada um responsável pelo preaquecimento de um motor Wartsila 20V32 de 8,73 MW, foram construídos, somando um total de 500 coletores solares instalados e uma superfície de captação solar total de 1000 metros quadrados. Uma estação meteorológica com sensores de radiação solar global, difusa, direta e temperatura ambiente foi posicionada do lado dos sistemas para medir as condições ambientais na região. A simulação do desempenho do sistema solar foi efetuada ao longo de um ano com dados de radiação solar da estação meteorológica de Buriticupu, no Maranhão, dados que mais se aproximam dos dados disponíveis de Miranda do Norte. Correlações para transformar a radiação global medida numa superfície horizontal para uma superfície inclinada foram selecionadas após uma revisão bibliográfica dentre as disponíveis na literatura. Diferentes cenários de controle do acionamento das bombas de água foram comparados a fim de determinar a melhor configuração de operação. A influência da temperatura de preaquecimento dos motores no desempenho do sistema solar foi avaliada também. Os resultados da simulação foram comparados com os resultados obtidos via o método F-CHART. Uma participação média anual da energia solar de 11,5 por cento foi encontrada para o preaquecimento dos motores levando a uma redução de 24693 kg/ano de óleo combustível usado na caldeira do sistema de preaquecimento dos motores da usina termelétrica.
The present work has as main objective the performance evaluation of a pilot system for preheating the engines of Gera Maranhão power plant, in Miranda do Norte, state of Maranhão, via thermal solar energy using a numerical simulation. Five independent subsystems, each one responsible for the preheating of a Wartsila 20V32 internal combustion engine of 8.73 MW, were installed. These systems amount five hundred solar collectors, with a total solar collecting area of 1000 square meters. A meteorological station with sensors for global, diffusive and beam solar radiation, as well as ambient temperature recorders, was placed by the side of the system in mode to measure ambient condition in the area. The simulation of the solar system performance was processed over a year with data of solar radiation for a meteorological station of Buriticupu, state of Maranhão, Brazil. Correlations to transform the global radiation measured on a horizontal plane to a sloped plane were selected, following a selection from a literature review. For the control of the water pumps, different scenarios were compared in order to determine the best operational configuration. The influence of engine preheating temperature in the performance of the solar system was also evaluated. Simulation results were compared with results obtained with the F-CHART method. An annual average solar energy contribution of 11.5 percent was found for the preheating of the engines. This resulted in a reduction of 24693 kg per year of fuel oil used in the boiler of the traditional preheating system of the power plant.
13
Johnston, Jon R. Jr. "Evaluation of expanders for use in a solar-powered Rankine Cycle Heat Engine." The Ohio State University, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=osu1298561887.
14
Chen, Dejin. "Untersuchungen zur Optimierung eines solaren Niedertemperatur-Stirlingmotors." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2005. http://nbn-resolving.de/urn:nbn:de:swb:14-1111049328086-35473.
Анотація:
Das Ziel der vorliegenden Dissertationsschrift bestand darin, für die äquatornahen Regionen mit hoher solarer Einstrahlung einen solaren Niedertemperatur-Stirlingmotor zu entwickeln, berechnen, konstruieren und fertigen, experimentelle Untersuchungen durchzuführen sowie die Ergebnisse auszuwerten. Des Weiteren war im Rahmen dieser Arbeiten die Gültigkeit der Schmidt-Theorie für den Niedertemperatur-Stirlingmotor zu überprüfen. Im Rahmen der durchgeführten Untersuchungen wurden drei Varianten des solaren Niedertemperatur-Stirlingmotors(Stirlingmotor III, IV und IV-A)konstruiert und gefertigt sowie mit Hilfe eines Sonnensimulators (800 W / m2) getestet. Zur Ermittlung der Heißgastemperatur wurde ein mathematisches Modell erstellt, dessen Gültigkeit für den solaren Niedertemperatur-Stirlingmotor durch umfangreiche Experimente bestätigt werden konnte. Die Voraussetzungen der Schmidt-Theorie sind relativ ideal und bei dem solaren Niedertemperatur-Stirlingmotor nicht erfüllt. Trotzdem ist die Schmidt-Theorie auch auf den Stirlingmotor anwendbar. Eine vereinfachte Beziehung zur Berechnung der Leistung (Gl. 3.80) wurde abgeleitet und experimentell überprüft. Die Leistungsoptimierung erfolgte unter Berücksichtigung des Einflusses von Phasenwinkel, Verdichtungsverhältnis und Drehzahl. Der optimale Bereich des Phasenwinkels liegt zwischen 60° und 100°, empfohlen wird ein Winkel von 90°. Der optimale Drehzahlbereich liegt zwischen 18 und 25 U / min. Solare Niedertemperatur-Stirlingmotoren zeichnen sich dadurch aus, dass sie immer die maximal mögliche mechanische Leistung abgeben, indem die Drehzahl sinkt und die Heißgastemperatur steigt. Die Reduzierung des Totvolumens ist für die Leistung des Niedertemperatur-Stirlingmotors von großer Bedeutung. So konnte durch das Einbringen eines Verdrängers in den Arbeitskolben die mechanische Leistung um etwa 10 % gesteigert werden. Weiterhin konnte experimentell nachgewiesen werden, dass sowohl das Anbringen der Abdeckungsfolie als auch der Einsatz eines Regenerators wichtige Voraussetzungen für den stabilen Betrieb des solaren Niedertemperatur-Stirlingmotors sind. Beim Stirlingmotor IV-A wurde neben der kontinuierlichen auch die diskontinuierliche Bewegung des Verdrängers realisiert. Die durchgeführten Versuche haben ergeben, dass bei letzterer Bewegungsart das übertragbare mechanische Moment größer ist. Voraussetzung für die diskontinuierliche Bewegung ist ein massenloser Verdränger. Dieser wurde durch das Anbringen von Ausgleichsgewichten verwirklicht. Die entsprechenden experimentellen Arbeiten führten zu dem Ergebnis, dass im Durchschnitt eine um ca. 10 % höhere mechanische Leistung erzielt werden kann. Im Ergebnis der durchgeführten theoretischen und experimentellen Untersuchungen an den drei Varianten des solaren Niedertemperatur-Stirlingmotors kann festgestellt werden, dass mit der Maschine IV-A die günstigsten Parameter erreicht wurden. Vorteilhaft bei dieser Version sind insbesondere einfachere Fertigung, gute Abdichtung, kleinere Strömungsverluste sowie eine um etwa 2 K niedrigere Kaltgastemperatur. Der Stirlingmotor IV-A sollte Prototyp für Feldtest werden.
15
Börner, Reina. "Modélisation d'échangeur de chaleur : analyse théorique et expérimentale du comportement en régime transitoire : particularisation aux capteurs solaires et optimisation des systèmes moteurs associés." Vandoeuvre-les-Nancy, INPL, 1995. http://www.theses.fr/1995INPL011N.
Анотація:
La filière solaire des centrales actuellement existantes se base essentiellement sur des cycles classiques à vapeur. Mais il est aussi possible de développer une filière gaz en utilisant des turbines à gaz avec des cycles ouverts ou fermés. Dans cette optique a été développée une méthode générale d'optimisation du rendement d'un système capteur solaire à air - moteur thermique, en s'appuyant sur un fonctionnement en cycle de CARNOT puis en cycle de BRAYTON avec ou sans régénération. Les écarts de température à la source et au puits, les pertes thermiques directes entre source et puits sont pris en compte, ainsi que le rendement de régénération pour le cycle de Brayton. L’étude de la sensibilité paramétrique est faite en prenant la température du puits ou la température de stagnation comme référence. Cette première partie se termine par la présentation de quelques résultats significatifs, permettant de situer l'importance de ces paramètres dans la conception des moteurs thermiques de ce type. Dans la deuxième partie, l'étude en régime de relaxation de flux radiatif de ces capteurs solaires comportant des matrices poreuses mène à l'écriture des équations de bilan d'énergie pour les phases solide et fluide. Leur résolution analytique simplifiée en négligeant les termes de diffusion dispersion et le terme d'inertie du fluide aboutit à des valeurs du coefficient volumique de transfert h qui s'accordent avec ceux du régime stationnaire. Le modèle numérique développe ensuite pour la résolution des équations complètes est basé sur la méthode des volumes finis et permet l'identification de h par comparaison des profils de température calculés et expérimentaux. Le présent travail se limite aux milieux poreux suivants: les copeaux de duralumin, la laine de cuivre, la mousse de polyuréthane et les grains de liège. Les valeurs de h déduites du modèle numérique transitoire restent très supérieures à celles déduites du modèle analytique correspondant, mais restent cohérents par rapport aux quelques corrélations de la littérature
16
Hoetman, Agus Rusyana. "A computational and experimental study of a solar powered Rankine cycle engine for use in Jakarta." Thesis, University of Salford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.292902.
17
Mardanpour, Pezhman. "Effects of engine placement and morphing on nonlinear aeroelastic behavior of flying wing aircraft." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50268.
Анотація:
Effects of engine placement on flutter characteristics of a very flexible high-aspect-ratio wing are investigated using the code NATASHA (Nonlinear Aeroelastic Trim And Stability of HALE Aircraft). The analysis was validated against published results for divergence and flutter of swept wings and found to be in excellent agreement with the experimental results of the classical wing of Goland. Moreover, modal frequencies and damping obtained for the Goland wing were found in excellent agreement with published results based on a new continuum-based unsteady aerodynamic formulation. Gravity for this class of wings plays an important role in flutter characteristics. In the absence of aerodynamic and gravitational forces and without an engine, the kinetic energy of the first two modes are calculated. Maximum and minimum flutter speed locations coincide with the area of minimum and maximum kinetic energy of the second bending and torsion modes. Time-dependent dynamic behavior of a turboshaft engine (JetCat SP5) is simulated with a transient engine model and the nonlinear aeroelastic response of the wing to the engine's time-dependent thrust and dynamic excitation is presented. Below the flutter speed, at the wing tip and behind the elastic axis, the impulse engine excitation leads to a stable limit cycle oscillation; and for the ramp kind of excitation, beyond the flutter speed, at 75% span, behind the elastic axis, it produces chaotic oscillation of the wing. Both the excitations above the flutter speed are stabilized, on the inboard portion of the wing.
Effects of engine placement and sweep on flutter characteristics of a backswept flying wing resembling the Horten IV are explored using NATASHA. This aircraft exhibits a non-oscillatory yawing instability, expected in aircraft with neither a vertical tail nor yaw control. More important, however, is the presence of a low frequency “body-freedom flutter” mode. The aircraft center of gravity was held fixed during the study, which allowed aircraft controls to trim similarly for each engine location, and minimized flutter speed variations along the inboard span. Maximum flutter speed occurred for engine placement just outboard of 60% span with engine center of gravity forward of the elastic axis. The body-freedom flutter mode was largely unaffected by the engine placement except for cases in which the engine is placed at the wing tip and near the elastic axis. In the absence of engines, aerodynamics, and gravity, a region of minimum kinetic energy density for the first symmetric free-free bending mode is also near the 60% span. A possible relationship between the favorable flutter characteristics obtained by placing the engines at that point and the region of minimum kinetic energy is briefly explored.
Effects of multiple engine placement on a similar type of aircraft are studied. The results showed that multiple engine placement increases flutter speed particularly when the engines are placed in the outboard portion of the wing (60% to 70% span), forward of the elastic axis, while the lift to drag ratio is affected negligibly. The behavior of the sub- and supercritical eigenvalues is studied for two cases of engine placement. NATASHA captures a hump body-freedom flutter with low frequency for the clean wing case, which disappears as the engines are placed on the wings. In neither case is there any apparent coalescence between the unstable modes. NATASHA captures other non-oscillatory unstable roots with very small amplitude, apparently originating with flight dynamics. For the clean-wing case, in the absence of aerodynamic and gravitational forces, the regions of minimum kinetic energy density for the first and third bending modes are located around 60% span. For the second mode, this kinetic energy density has local minima around the 20% and 80% span. The regions of minimum kinetic energy of these modes are in agreement with calculations that show a noticeable increase in flutter speed at these regions if engines are placed forward of the elastic axis.
High Altitude, Long Endurance (HALE) aircraft can achieve sustained, uninterrupted flight time if they use solar power. Wing morphing of solar powered HALE aircraft can significantly increase solar energy absorbency. An example of the kind of morphing considered in this thesis requires the wings to fold so as to orient a solar panel to be hit more directly by the sun's rays at specific times of the day. In this study solar powered HALE flying wing aircraft are modeled with three beams with lockable hinge connections. Such aircraft are shown to be capable of morphing passively, following the sun by means of aerodynamic forces and engine thrusts. The analysis underlying NATASHA was extended to include the ability to simulate morphing of the aircraft into a “Z” configuration. Because of the “long endurance” feature of HALE aircraft, such morphing needs to be done without relying on actuators and at as near zero energy cost as possible. The emphasis of this study is to substantially demonstrate the processes required to passively morph a flying wing into a Z-shaped configuration and back again.
18
Macháček, Jan. "Stirlingův termodynamický cyklus." Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2009. http://www.nusl.cz/ntk/nusl-233504.
Анотація:
My doctoral thesis deals with study and analyse of Stirling thermodynamical cycle. Cycle that is composed of two isochoras and two isotherms. I describe functional principle of Stirling engine and all its parts, constructional variations of pistons system and possible engine working modes. Next chapter contains analyse of engine constructional parameters. Measuring of torque and load characteristics, p - V schemes and output work for various engine inputs is part of this analyse. There is composed mathematical engine characterization by means of Schmidt theory in chapter five. Mathematical characterization is consequently applied to engine model. Theoretical analysis and practical measurement were base for concepts, realization and verification of constructional correction. One part of my thesis is attended to design of new lamella for regenerative exchanger. For optimal lamella constructional proportions were used computational algorithm and simulations. There is concept of cogeneration unit with Stirling engine and its benefits check in last chapter. General theoretical and practical analyse of workable Stirling engine is result of my thesis. Analyse in this extent was not nowhere publishing yet. Design of regenerative exchanger lamella is then practical input of my thesis.
19
Chen, Dejin. "Untersuchungen zur Optimierung eines solaren Niedertemperatur-Stirlingmotors." Doctoral thesis, [S.l.] : [s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=974523542.
20
Recht, Daniel. "Energetic Beam Processing of Silicon to Engineer Optoelectronically Active Defects." Thesis, Harvard University, 2012. http://dissertations.umi.com/gsas.harvard:10305.
Анотація:
This thesis explores ways to use ion implantation and nanosecond pulsed laser melting, both energetic beam techniques, to engineer defects in silicon. These defects are chosen to facilitate the use of silicon in optoelectronic applications for which its indirect bandgap is not ideal. Chapter 2 develops a kinetic model for the use of point defects as luminescence centers for light-emitting diodes and demonstrates an experimental procedure capable of high-throughput screening of the electroluminescent properties of such defects. Chapter 3 discusses the dramatic change in optical absorption observed in silicon highly supersaturated (i.e., hyperdoped) with the chalcogens sulfur, selenium, and tellurium and reports the first measurements of the optical absorption of such materials for photon energies greater than the bandgap of silicon. Chapter 3 examines the use of silicon hyperdoped with chalcogens in light detectors and concludes that while these devices display strong internal gain that is coupled to a particular type of surface defect, hyperdoping with chalcogens does not lead directly to measurable sub-bandgap photoconductivity. Chapter 4 considers the potential for Silicon to serve as the active material in an intermediate-band solar cell and reports experimental progress on two proposed approaches for hyperdoping silicon for this application. The main results of this chapter are the use of native-oxide etching to control the surface evaporation rate of sulfur from silicon and the first synthesis of monocrystalline silicon hyperdoped with gold.Engineering and Applied Sciences
21
Sakai, Tadashi. "A Study of Variable Thrust, Variable Specific Impulse Trajectories for Solar System Exploration." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/4904.
Анотація:
A study has been performed to determine the advantages and disadvantages of variable thrust and variable specific impulse (Isp) trajectories for solar system exploration.
There have been several numerical research efforts for variable thrust, variable Isp, power-limited trajectory optimization problems. All of these results conclude that variable thrust, variable Isp (variable specific impulse, or VSI) engines are superior to constant thrust, constant Isp (constant specific impulse, or CSI) engines. However, most of these research efforts assume a mission from Earth to Mars, and some of them further assume that these planets are circular and coplanar. Hence they still lack the generality.
This research has been conducted to answer the following questions:
- Is a VSI engine always better than a CSI engine or a high thrust engine for any mission to any planet with any time of flight considering lower propellant mass as the sole criterion?
- If a planetary swing-by is used for a VSI trajectory, is the fuel savings of a VSI swing-by trajectory better than that of a CSI swing-by or high thrust swing-by trajectory?
To support this research, an unique, new computer-based interplanetary trajectory calculation program has been created. This program utilizes a calculus of variations algorithm to perform overall optimization of thrust, Isp, and thrust vector direction along a trajectory that minimizes fuel consumption for interplanetary travel. It is assumed that the propulsion system is power-limited, and thus the compromise between thrust and Isp is a variable to be optimized along the flight path. This program is capable of optimizing not only variable thrust trajectories but also constant thrust trajectories in 3-D space using a planetary ephemeris database. It is also capable of conducting planetary swing-bys.
Using this program, various Earth-originating trajectories have been investigated and the optimized results have been compared to traditional CSI and high thrust trajectory solutions. Results show that VSI rocket engines reduce fuel requirements for any mission compared to CSI rocket engines. Fuel can be saved by applying swing-by maneuvers for VSI engines, but the effects of swing-bys due to VSI engines are smaller than that of CSI or high thrust engines.
22
Dentello, Rodrigo Orefise [UNESP]. "Estudo de geração de energia elétrica em motores stirling acionados por biogás e/ou energia solar." Universidade Estadual Paulista (UNESP), 2017. http://hdl.handle.net/11449/151835.
Анотація:
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
O motor Stirling é um motor de combustão externa que opera com diferenças de temperaturas, produzindo trabalho mecânico e eletricidade. Esse tipo de motor opera em um ciclo fechado, que através do uso de uma fonte quente e uma fria, expande e comprime um fluido de trabalho (ar, hélio ou hidrogênio, dentre os mais comuns), fornecendo assim o movimento de um pistão. Pode operar com calor residual e também com a queima de qualquer tipo de combustível (gás natural, diesel, gasolina, etc). Essa tecnologia tem se destacado para o desenvolvimento de sistemas que operam com biocombustíveis (biogás e syngas) e com energias renováveis, como por exemplo, caso de uso de concentradores solares. Este trabalho tem como objetivo estudar as performances termodinâmica, econômica e ambiental de um sistema Stirling operando com sistema de alimentação a biogás e energia solar, aplicado para a geração de energia elétrica descentralizada. São realizados estudos dos aspectos termodinâmicos do ciclo Stirling, com foco no funcionamento e no trabalho do motor. São efetuadas análises técnicas do sistema operando com câmara de combustão a biogás e utilizando energia de concentrador solar parabólico. Em etapa final são analisados e comparados os aspectos econômicos e ambientais do sistema acionado por biogás e energia solar. Os resultados obtidos mostraram pela teoria de Schmidt uma eficiência do motor Stirling de 67%. Da análise econômica, fica evidente que um maior número de horas de operação corrobora com a viabilidade econômica. Quantos aos aspectos ambientais, o valor da eficiência ecológica do motor Stirling operando a biogás é de 98,02%. No caso do sistema solar utilizando concentrador para alimentar o motor Stirling, a eficiência ecológica indica é de cerca de 98%. Conclui-se que o uso de fontes renováveis, permitem bons níveis de eficiência de geração de energia elétrica de sistemas utilizando motores Stirling de pequeno porte, reduzindo níveis de poluição atmosférica e contribuindo para a redução do efeito estufa.
The Stirling engine is an external combustion engine that operates at varying temperatures, producing mechanical work or electricity. This type of engine operates in a closed cycle, which through the use of a hot and cold source expands and compresses a working fluid (air, helium or hydrogen, among the most common), thus providing the movement of a piston. It can operate with residual heat and also with the burning of any type of fuel (natural gas, diesel, gasoline, etc.). This technology has been outstanding for the development of hybrid systems that operate with biofuels (biogas and syngas) and with renewable energies, as for example, case of use of solar concentrators. This work aims to study the thermodynamic, economic and environmental performances of a Stirling system operating with a biogas and solar energy supply system, applied for the generation of decentralized electric energy. Studies are carried out on the thermodynamic aspects of the Stirling cycle, focusing on the operation and work of the engine. Technical analysis of the system is carried out using a biogas combustion chamber and using parabolic solar concentrator energy. In the final stage are analyzed and compared the economic and environmental aspects of the system activated by biogas and solar energy. The results showed that through the thermodynamic analysis by the Schmidt theory, a Stirling engine efficiency of 67% was obtained. From the economic analysis, it is evident that a greater number of hours of operation corroborates with economic viability. As for the environmental aspects, the ecological efficiency value of the Stirling engine operating biogas is 98.02%. In the case of the solar system using concentrator to power the Stirling engine, the ecological efficiency indicates is about 98%. It is concluded that the use of renewable sources, allow good levels of efficiency of electric power generation of systems using small Stirling motors, reducing levels of air pollution and contributing to the reduction of the greenhouse effect.
23
Joshi, Keyur Bhanuprasad. "Modeling of Bio-inspired Jellyfish Vehicle for Energy Efficient Propulsion." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/19256.
Анотація:
Jellyfish have inhabited this planet for millions of years and are the oldest known metazoans that swim using muscles. They are found in freshwater sources and in oceans all over the world. Over millions of years of evolution, they have adapted to survive in a given environment. They are considered as one of the most energy efficient swimmers. Owing to these characteristics, jellyfish has attracted a lot of attention for developing energy efficient unmanned undersea vehicles (UUVs).The goal of this thesis is to provide understanding of the different physical mechanisms that jellyfish employs to achieve efficient swimming by using analytical and computational models. The models were validated by using the experimental data from literature. Based upon these models refinements and changes to engineering vehicles was proposed that could lead to significant enhancement in propulsion efficiency. In addition to the propulsion, the thesis addresses the practical aspects of deploying a jellyfish-inspired robotic vehicle by providing insights into buoyancy control and energy generation. The thesis is structured in a manner such that propulsive and structural models inspired from the natural animal were systematically combined with the practical aspects related to ionic diffusion driven buoyancy control system and thermal -- magnetic energy harvesting system. Jellyfish morphology, swimming mechanism and muscle architecture were critically reviewed to accurately describe the natural behavior and material properties. We provide full understanding of mesoglea, which plays most significant role towards swimming performance, in terms of composition, mechanical properties and nonlinear dynamics. Different jellyfish species exhibit different microstructure of mesoglea and thus there is a wide variety of soft materials. Mechanical properties of collagen fibers that form the main constituent toward imparting elasticity to mesoglea were reviewed and analyzed. The thesis discusses the theoretical models describing the role of structure of mesoglea towards its mechanical properties and explains the variation occurring in stiffness under given experimental environment. Muscle architecture found in jellyfish, nerve nets and its interconnection with the muscles were investigated to develop comprehensive understanding of jellyfish propulsion and its reaction to external stimuli.
Different muscle arrangements were studied including radial, coronal muscle, and coronal-muscles-with-breaks in-between them as observed in Cyanea capillata. We modeled these muscle arrangements through finite element modeling (FEM) to determine their deformation and stroke characteristics and their overall role in bell contraction. We found that location and arrangement of coronal muscle rings plays an important role in determining their efficient utilization.
Once the understanding of natural jellyfish was achieved, we translated the findings onto artificial jellyfish vehicle designed using Bio-inspired Shape Memory Alloy Composite (BISMAC) actuators. Detailed structural modeling was conducted to demonstrate deformation similar to that of jellyfish bell. FEM model incorporated hyperelastic behavior of artificial mesoglea (Ecoflex-0010 RTV, room temperature vulcanizing silicone with shore hardness (0010)), experimentally measured SMA temperature transformation, gravity and buoyancy forces. The model uses the actual control cycle that was optimized for driving the artificial jellyfish vehicle "robojelly". Using a comparative analysis approach, fundamental understanding of the jellyfish bell deformation, thrust generation, and mechanical efficiency were provided.
Meeting energy needs of artificial vehicle is of prime importance for the UUVs. Some jellyfish species are known to use photosynthesis process indirectly by growing algae on their exumbrella and thereby utilizing the sunlight to generate energy. Inspired by this concept, an extensive model was developed for harvesting solar energy in underwater environment from the jellyfish bell structure. Three different species were modeled for solar energy harvesting, namely A.aurita, C.capillata and Mastigia sp., using the amorphous silicon solar cell and taking into account effect of fineness ratio, bell diameter, turbidity, depth in water and incidence angle. The models shows that in shallow water with low turbidity a large diameter vehicle may actually generate enough energy as required for meeting the demand of low duty cycle propulsion. In future, when the solar energy harvesting technology based upon artificial photosynthesis, referred to as "dye-sensitized solar cells", matures the model presented here can be easily extended to determine its performance in underwater conditions.
In order to supplement the energy demand, a novel concept of thermal -- magnetic energy harvesting was developed and extensively modeled. The proposed harvester design allows capturing of even small temperature differences which are difficult for the thermoelectrics. A systematic step-by-step model of thermo-magnetic energy harvester was presented and validated against the experimental data available in literature. The multi-physics model incorporates heat transfer, magnetostatic forces, mechanical vibrations, interface contact behavior, and piezoelectric based energy converter. We estimated natural frequency of the harvester, operating temperature regimes, and electromechanical efficiency as a function of dimensional and physical variables. The model provided limit cycle operation regimes which can be tuned using physical variables to meet the specific environment.
Buoyancy control is used in aquatic animals in order to maintain their vertical trajectory and travel in water column with minimum energy expense. Some crustaceans employ selective ion replacement of heavy or lighter ions in their dorsal carapace. A model of a buoyancy chamber was developed to achieve similar buoyancy control using electro-osmosis. The model captures all the essential ionic transport and electrochemistry to provide practical operating cycle for the buoyancy engine in the ocean environment.
Ph. D.
24
Ramsell, Daniel. "Improve and optimize search engine : To provide better and relevant content for the customer." Thesis, Mittuniversitetet, Institutionen för informationssystem och –teknologi, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-36805.
Анотація:
This report has conducted a research of comparing a few open source search engines. The research contains two evaluation processes, the first evaluation will evaluate each open source search engine found on today’s market. Points will be given between one to five points depending on how well the open source search engine meets the requirements. The open source search engine with the highest score will then be chosen for implementation. The first evaluation resulted in Elasticsearch being the selected open source search engine and will continue to the implementation phase. The second evaluation will be measuring the system performance and the relevance of the SERP (Search Engine Results Pages). This phase will evaluate the system performance by taking time measurements on how long it takes for the search engines to deliver the SERP. The relevance of the search results will be judge by a group of CSN employers. The group will be giving point be-tween one to five points depending on the relevance of the SERP. It will eval-uate Elasticsearch with the search engine CSN are using today on their web-site (www.csn.se). This phase resulted in Elasticsearch being the better in performance measurements but not in the relevance of the SERP. This was discussed and came to the conclusion that most points were lost because of the first search result Elasticsearch delivered. If this search result was re-moved Elasticsearch could deliver as good results as the old search engine. The survey came to the conclusion that Elasticsearch is recommended for CSN if certain problem areas could be corrected before implementation into their systems.
25
Dočekal, David. "Měřicí pracoviště pro systém vzdálené dodávky energie." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2016. http://www.nusl.cz/ntk/nusl-242852.
Анотація:
This thesis is focused on the creation of measuring workplace for remote power supply system. This is the measuring of the workplace, engaged in the processing of measured data, the production of electrical energy made by a photovoltaic panel and wind turbines. In the theoretical part, the reader is familiar with the issue of renewable energy sources. The first chapter is about the energy of the wind. Here is described the emergence of the wind, the basic division of wind power, through the production of electrical energy to the measurement itself. The second chapter deals with the solar energy. This chapter describes the emergence of the solar energy, photoelectric effect, description of characteristic features and related evaluation of the photovoltaic panel. The reader learns the basic distribution photovoltaic panels here and their manufacturing. The third chapter is devoted to measurement methods and specifying the basic conditions for the evaluation of the operation of wind turbines and photovoltaic panel. In the fourth chapter describes the basic data on individual facilities, which have been selected for this thesis and the involvement of the measuring site. There is also included wind power JPT-100 photovoltaic panels A-130 anemometer TX20ETH, pyranometer SG420 and temperature sensor PT100. Measuring software is described in the fifth chapter. In the last chapter, contains the experimental measurements in the selected time interval and the actual evaluation.
26
Strava, Jan. "Konstrukce malého parního motoru pro využití sluneční energie." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-417723.
Анотація:
Possible modern application of piston steam engine is electricity production using steam made by solar energy. This diploma thesis focuses on designing such piston steam engine Described solution would be effective as an off grid electricity generator, because alternative source of steam could be added for occasions, when sunlight is not powerfull enough for steam production.
27
Qandil, Hassan Darwish Hassan. "Investigations of the Fresnel Lens Based Solar Concentrator System through a Unique Statistical-Algorithmic Approach." Thesis, University of North Texas, 2019. https://digital.library.unt.edu/ark:/67531/metadc1609121/.
Анотація:
This work investigates the Fresnel-lens-based solar concentrator-receiver system in a multi-perspective manner to design, test and fabricate this concentrator with high-efficiency photon and heat outputs and a minimized effect of chromatic aberrations. First, a MATLAB®-incorporated algorithm optimizes both the flat-spot and the curved lens designs via a statistical ray-tracing methodology of the incident light, considering all of its incidence parameters. The target is to maximize the solar ray intensity on the receiver's aperture, and therefore, achieve the highest possible focal flux. The algorithm outputs prismatic and dimensional geometries of the Fresnel-lens concentrator, which are simulated by COMSOL® Multiphysics to validate the design. For the second part, a novel genetically-themed hierarchical algorithm (GTHA) has been investigated to design Fresnel-lens solar concentrators that match with the distinct energy input and spatial geometry of various thermal applications. Basic heat transfer analysis of each application decides its solar energy requirement. The GTHA incorporated in MATLAB® optimizes the concentrator characteristics to secure this energy demand, balancing a minimized geometry and a maximized efficiency. Two experimental applications were selected from literature to validate the optimization process, a solar welding system for H13 steel plates and a solar Stirling engine with an aluminum-cavity receiver attached to the heater section. In each case, a flat Fresnel-lens with a spot focus was algorithmically designed to supply the desired solar heat, and then a computer simulation of the optimized lens was conducted showing great comparability to the original experimental results. Thirdly, the prismatic geometry of the Fresnel lens was further optimized through a statistical approach that incorporates laws of light refraction and trigonometry. The proposed design produces high focal irradiance that is more suitable for thermal applications. The motivation was to enhance the tolerability of a flat Fresnel-lens concentrator to tracking errors, without the use of secondary optics or sophisticated, and normally costly, meticulous tracking equipment. A comparative simulation analysis was conducted for two case studies from literature, each with a different design method. Fresnel lenses optimized by this work enhanced the concentration acceptance product (CAP) significantly, compared to that in literature. Then, this work introduced an innovative code-based, detailed, and deterministic geometrical approach, which couples the optimization of the Fresnel lens primary optical element (POE) and the dome-shaped secondary optical element (SOE). The objective was to maximize the concentration acceptance product, while using the minimum SOE and receiver geometries at a given f-number and incidence angle (also referred to as the tracking error angle). The laws of polychromatic light refraction along with trigonometry and spherical geometry were utilized to optimize the POE grooves, SOE radius, receiver size, and SOE–receiver spacing. Two literature case studies were analyzed to verify this work's optimization, and the equivalent POEs designed by this work, with optimized SOEs, showed a significant enhancement in the CAP values compared to that of literature. Lastly, four methods for prototyping the Fresnel lens were discussed and experimentally tested; 3D printing, acrylic resin casting, direct CNC machining in acrylic and hot embossing. Once tested, the methods of CNC machining and hot embossing of acrylic proved to be the most promising in terms of cost, fabrication time, and concentration effectiveness. Future work will focus on enhancing the algorithmic design and improving the quality of lens fabrication.
28
Rahmani, Mustapha Amine. "Gestion de l'énergie d'une micro-centrale solaire thermodynamique." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENT077/document.
Анотація:
Cette thèse s'inscrit dans le cadre du projet collaboratif MICROSOL, mené par Schneider Electric, et qui oeuvre pour le développement de micros centrales solaires thermodynamiques destinées à la production d'électricité en sites isolés (non connectés au réseau électrique) en exploitant l'énergie thermique du soleil. Le but de cette thèse étant le développement de lois de commande innovantes et efficaces pour la gestion de l'énergie de deux types de micros centrales solaires thermodynamiques : à base de moteur à cycle de Stirling et à base de machines à Cycle de Rankine Organique (ORC). Dans une première partie, nous considérons une centrale solaire thermodynamique à base de machine à cycle de Stirling hybridée à un supercondensateur comme moyen de stockage d'énergie tampon. Dans ce cadre, nous proposons une première loi de commande validée expérimentalement, associée au système de conversion d'énergie du moteur Stirling, qui dote le système de performances quasi optimales en termes de temps de réponse ce qui permet de réduire la taille du supercondensateur utilisé. Une deuxième loi de commande qui gère explicitement les contraintes du système tout en dotant ce dernier de performances optimales en terme de temps de réponse, est également proposée. Cette dernière loi de commande est en réalité plus qu'un simple contrôleur, elle constitue une méthodologie de contrôle applicable pour une famille de systèmes de conversion de l'énergie.Dans une deuxième partie, nous considérons une centrale solaire thermodynamique à base de machine à cycle de Rankine Organique (ORC) hybridée à un banc de batteries comme moyen de stockage d'énergie tampon. Etant donné que ce système fonctionne à vitesse de rotation fixe pour la génératrice asynchrone qui est connectée à un système de conversion d'énergie commercial, nous proposons une loi de commande prédictive qui agit sur la partie thermodynamique de ce système afin de le faire passer d'un point de fonctionnement à un autre, lors des appels de puissance des charges électriques, le plus rapidement possible (pour réduire le dimensionnement des batteries) tout en respectant les contraintes physiques du système. La loi de commande prédictive développée se base sur un modèle dynamique de la machine ORC identifié expérimentalement grâce à un algorithme d'identification nonlinéaire adéquatThis Ph.D thesis was prepared in the scope of the MICROSOL project, ledby Schneider Electric, that aims at developing Off-grid solar thermodynamic micro powerplants exploiting the solar thermal energy. The aim of this thesis being the development of innovative and efficient control strategies for the energy management of two kinds of solar thermodynamic micro power plants: based on Stirling engine and based and Organic RankineCycle (ORC) machines.In a first part, we consider the Stirling based solar thermodynamic micro power planthybridized with a supercapacitor as an energy buffer. Within this framework, we propose afirst experimentally validated control strategy, associated to the energy conversion system ofthe Stirling engine, that endows the system with quasi optimal performances in term of settlingtime enabling the size reduction of the supercapacitor. A second control strategy that handlesexplicitly the system constraints while providing the system with optimal performances interm of settling time , is also proposed. This control strategy is in fact more than a simplecontroller, it is a control framework that holds for a family of energy conversion systems.In a second part, we consider the Organic Rankine Cycle (ORC) based thermodynamicmicro power plant hybridized with a battery bank as an energy buffer. Since this system worksat constant speed for the asynchronous generator electrically connected to a commercial energyconversion system, we propose a model predictive controller that acts on the thermodynamicpart of this system to move from an operating point to another, during the load power demandtransients, as fast as possible (to reduce the size of the battery banks) while respecting thephysical system constraints. The developed predictive controller is based upon a dynamicmodel, for the ORC power plant, identified experimentally thanks to an adequate nonlinearidentification algorithm
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Filho, Ari do Amaral Torres. "AnÃlise da utilizaÃÃo de mÃtodos Ãgeis no desenvolvimento de ambientes virtuais de aprendizagem: um estudo de caso do Solar 2.0." Universidade Federal do CearÃ, 2014. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=12689.
Анотація:
FundaÃÃo de Amparo à Pesquisa do Estado do CearÃNas duas Ãltimas dÃcadas houve um considerÃvel avanÃo no uso de Tecnologias da InformaÃÃo e ComunicaÃÃo Digitais no processo de ensino e aprendizagem, tanto na modalidade de EducaÃÃo presencial quanto a distÃncia. Neste contexto, o uso de Ambientes Virtuais de Aprendizagem - softwares criados para o suporte a cursos atravÃs da Internet - vÃm crescendo e seu acesso se tornando cada vez mais diversificado, indo de computadores desktop a celulares smartphones. Desta forma, a complexidade de criaÃÃo destes ambientes se torna cada vez maior e exige tÃcnicas de Engenharia de Software e GestÃo de Projetos cada vez melhores para garantir a qualidade do produto gerado e a satisfaÃÃo do cliente. Tendo em vista tal cenÃrio, o presente trabalho propÃe o uso de Metodologias Ãgeis tanto no desenvolvimento quanto na gestÃo de projetos de ambientes virtuais como uma soluÃÃo mais interessante que a tradicional forma de criaÃÃo de softwares baseada somente na qualidade do produto, esquecendo, muitas vezes, a satisfaÃÃo do cliente e a motivaÃÃo dos desenvolvedores
In the last two decades there has been considerable progress in the use of Information Technologies and Digital Communication in the process of teaching and learning, both in the form of classroom education as distance. In this context, the use of Virtual Learning Environments - software designed to support the courses via the Internet - is growing and access becoming increasingly diverse, ranging from desktop computers to mobile smartphones. Thus, the complexity of creating these environments becomes increasingly technical and requires Software Engineering and Project Management always better to ensure product quality and customer satisfaction generated. Given such a scenario, this paper proposes the use of Agile methodologies in the development and project management of virtual environments as a more interesting way than traditional software delivery based only on product quality, forgetting often , customer satisfaction and motivation of developers. This paper reports the adoption of agile methodologies in the development of the SOLAR AVA 2.0, showing that it is possible to succeed in both the technical level and at the organizational and personally with the adoption of agile practices in the development of AVAs that can be proven through experiments done with the satisfaction surveys with users and project developers.
30
Andrabi, Liaqat Hussain. "Intelligent Retrieval and Clustering of Inventions." Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-187018.
Анотація:
Ericsson’s Region IPR & Licensing (RIPL) receives about 3000 thousands Invention Disclosures (IvDs) every year submitted by researchers as a result of their R&D activities. To decide whether an IvD has a good business value and a patent application should be filed; a rigorous evaluation process is carried out by a selected Patent Attorney (PA). One of most important elements of the evaluation process is to find prior art similar, including similar IvDs that have been evaluated before. These documents are not public and therefore can’t be searched using available search tools. For now the process of finding prior art is done manually (without the help of any search tools) and takes up significant amount of time. The aim of this Master’s thesis is to develop and test an information retrieval search engine as a proof of concept to find similar Invention Disclosure documents and related patent applications. For this purpose, a SOLR database server is setup with up to seven thousand five hundred (7500) IvDs indexed. A similarity algorithm is implemented which is customized to weight different fields. LUCENE is then used to query the server and display the relevant documents in a web application.
31
Ali, Miran. "Changing a user’s search experience byincorporating preferences of metadata." Thesis, KTH, Skolan för datavetenskap och kommunikation (CSC), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-154608.
Анотація:
Implicit feedback is usually data that comes from users’ clicks, search queries and text highlights. It exists in abun- dance, but it is riddled with much noise and requires advanced algorithms to properly make good use of it. Several findings suggest that factors such as click-through data and reading time could be used to create user behaviour models in order to predict the users’ information need. This Master’s thesis aims to use click-through data and search queries together with heuristics to create a model that prioritises metadata-fields of the documents in order to predict the information need of a user. Simply put, implicit feedback will be used to improve the precision of a search engine. The Master’s thesis was carried out at Findwise AB - a search engine consultancy firm. Documents from the benchmark dataset INEX were indexed into a search engine. Two different heuristics were proposed that increment the priority of different metadata-fields based on the users’ search queries and clicks. It was assumed that the heuristics would be able to change the listing order of the search results. Evaluations were carried out for the two heuristics and the unmodified search engine was used as the baseline for the experiment. The evaluations were based on simulating a user that searches queries and clicks on documents. The queries and documents, with manually tagged relevance, used in the evaluation came from a data set given by INEX. It was expected that listing order would change in a way that was favourable for the user; the top-ranking results would be documents that truly were in the interest of the user. The evaluations revealed that the behaviour of the heuristics and the baseline have erratic behaviours and metrics never converged to any specific mean-relevance. A statistical test revealed that there is no difference in accuracy between the heuristics and the baseline. These results mean that the proposed heuristics do not improve the precision of the search engine and several factors, such as the indexing of too redundant metadata, could have been responsible for this outcome.Implicit feedback är oftast data som kommer från användarnas klick, sökfrågor och textmarkeringar. Denna data finns i överflöd, men har för mycket brus och kräver avancerade algoritmer för att man ska kunna dra nytta av den. Flera rön föreslår att faktorer som klickdata och läsningstid kan användas för att skapa beteendemodeller för att förutse användarens informationsbehov. Detta examensarbete ämnar att använda klickdata och sökfrågor tillsammans med heuristiker för att skapa en modell som prioriterar metadata-fält i dokument så att användarens informationsbehov kan förutses. Alltså ska implicit feedback användas för att förbättra en sökmotors precision. Examensarbetet utfördes hos Findwise AB - en konsultfirma som specialiserar sig på söklösningar. Dokument från utvärderingsdatamängden INEX indexerades i en sökmotor. Två olika heuristiker skapades för att ändra prioriteten av metadata-fälten utifrån användarnas sök- och klickdata. Det antogs att heuristikerna skulle kunna förändra ordningen av sökresultaten. Evalueringar utfördes för båda heuristiker och den omodifierade sökmotorn användes som måttstock för experimentet. Evalueringarna gick ut på att simulera en användare som söker på frågor och klickar på dokument. Dessa frågor och dokument, med manuellt taggad relevansdata, kom från en datamängd som tillhandahölls av INEX. Evalueringarna visade att beteendet av heuristikerna och måttstocket är slumpmässiga och oberäkneliga. Ingen av heuristikerna konvergerar mot någon specifik medelrelevans. Ett statistiskt test visar att det inte är någon signifikant skillnad på uppmätt träffsäkerhet mellan heuristikerna och måttstocket. Dessa resultat innebär att heuristikerna inte förbättrar sökmotorns precision. Detta utfall kan bero på flera faktorer som t.ex. indexering av överflödig meta-data.
32
Tîrcă-Dragomirescu, Georgiana. "Optimisation exergoéconomique des systèmes de trigénération d'énergie." Thesis, Université de Lorraine, 2012. http://www.theses.fr/2012LORR0164/document.
Анотація:
Voir résumé étendu en français en fin de thèseIn the actual energetic and economic context, energy polygeneration represents the answer regarding the efficient use of a fuel. This solution would diminish the losses associated to the classical methods of energy production and, as a result, would increase the installations' efficiency. The polygeneration systems (cogeneration/trigeneration of energy), consist of various technologies that offer alternatives to the global problems linked to energy, such as energy scarcity, energy supply security, emissions control from the production of energy, economy and energy conservation, etc.. This doctoral thesis examines two types of polygeneration of energy. The first part focuses on the analysis of a high power trigeneration system based on a gas turbine installation for production of electrical energy, the second part of the thesis is dealing with a system of micro-cogeneration of energy powered by a solar Stirling engine. Given the actuality and interest for the polygeneration field of energy production, there is a constant concern to simulate and optimize the operation of this kind of systems in order to achieve significant performance designed to satisfy the consumers' needs
33
Vedin, Felix, and Camilla Sandström. "A comparison study of PV and battery technologies for EWB off-grid electrification projects in Sub-Saharan Africa." Thesis, KTH, Hållbar utveckling, miljövetenskap och teknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-235497.
Анотація:
Only 10 % of the rural population in Sub-Saharan Africa has access to electricity. At the same time the Sub-Saharan countries are close to the equator and get many sun hours a day, leading to a huge potential for solar energy. This report aims to compare different PV system components for use in Sub-Saharan Africa to facilitate EWB for their work in electrification projects in the areas. The PV system will be compared with the following factors: economic, adoptability, scalability, environmental impact and efficiency, weighed in that order. A case simulation was made for a village around Nairobi were 20 households would be supplied with solar power. Both Polycrystalline silicon cells and thin filmed CIGS were simulated were the Poly c-Si cell was both the cost-efficient and scalable choice. Poly c-Si cells was also concluded to be advantageous of the crystalline cells by the chosen factors. Pb-acid batteries are best suited for off grid PV systems in rural areas. Different types of Pb-acid batteries can be used depending on the area’s typology. Off grid solar powered microgrids could be the solutions for an increased socioeconomic wellbeing for communities in rural areas.Endast 10% av lantbygdens befolkning i Subsahariska Afrika har tillgång till elektricitet. Samtidigt ligger de Subsahariska länderna nära ekvatorn och får många soltimmar per dygn, vilket leder till en stor potential för solenergi. Den här rapporten syftar till att jämföra olika solcellssystems komponenter för användning i östra Afrika för att främja Ingenjörer Utan Gränsers arbete inom elektrifierings projekt i området. Jämförelsen kommer utföras med följande faktorer, ekonomi, anpassningsförmåga, skalning, miljöpåverkan och effektivitet, viktat i den ordningen. En simulation gjordes för en by i området av Nairobi där 20 hushåll skulle få tillgång till solenergi. Både Poly kristallina celler och tunnfilm CIGS simulerades där Poly kristallina celler var både kostnadseffektivast samt det plats effektivaste valet. Polykristallina celler var även konkluderades vara det fördelaktiga valet av de kristallina cellerna utefter de valda faktorerna. Bly-syra batterier var bäst lämpade för själv stående solcellssystem på landsbygden. Olika typer av bly-syra batterier kan användas beroende på områdets typologi. Fristående solcellssystem kan vara en lösning till ett ökat socioekonomisk välmående för samhällen på landsbygden.
34
Nico, Thibaut. "Étude et développement de solutions de relocalisation d'objets sous-marins par des véhicules sous-marins hétérogènes." Thesis, Brest, École nationale supérieure de techniques avancées Bretagne, 2019. http://www.theses.fr/2019ENTA0005.
Анотація:
Dans le contexte de guerre des mines (MCM), il est important de revisiter les objets potentiellement dangereux afin de les identifier et les neutraliser s’il s’agit effectivement de mines. Cette dangereuse tâche était habituellement réalisée par des plongeurs démineurs qui sont petit à petit remplacés par des drones sous-marins. Le design « low cost » des robots de revisite/destruction de mines ne permet en général pas de garantir la revisite d’une cible géolocalisée en allant droit dessus. De plus, le robot pourrait commencer sa mission sous-marine à une distance éloignée et l’absence de positionnement GPS en environnement sous-marin imposent l’élaboration d’une stratégie afin de garantir la revisite de la cible. En se basant sur des informations a priori de l’environnement et notamment la présence de points de repère (amers), le problème est résolu par la planification d’une stratégie à suivre en prenant en compte les incertitudes de déplacement inhérentes en milieu sous-marin. Dans un contexte d’erreurs bornées, une approche ensembliste est proposée. Premièrement, en se basant sur la position et la forme des amers, ainsi que la zone visible du capteur embarqué, les cartes de recalages sont construites afin de définir les poses du robot qui permettent de détecter les différents amers afin de réduire l’incertitude de position du robot.Deuxièmement, en se basant sur un modèle paramétrique de déplacement avec des paramètres incertains, une stratégie haut-niveau est proposée à travers l’optimisation d’un graphe. La stratégie consiste à naviguer entre les cartes de recalage afin de réduire l’incertitude de position du robot et finalement garantir la revisite de la cible souhaitéeIn the Mine Counter Measure (MCM) context in the underwater environment, it is vital to revisit some potentially dangerous objects to identify and neutralize them if they are actually mines. This dangerous task was usually performed by humandivers but more and more it is conducted by unmanned underwater robots. Due to the low cost design of the revisit/mine-killer robot, going straightforward to the geolocalized suspicious object does not guarantee that the robot will redetect it.Moreover the robot may dive at a far position from the target and the lack of absolute positioning system in underwater environment demands a strategy to follow to guarantee the revisit of this target. Based on a priori information in the working area and especially the presence of geolocalized landmarks, the problem is solved as a motion planning problem considering uncertainties due to the increasing error when navigating underwater. In the context of bounded errors, the problem is solved in a set-membership manner. Firstly, based on the location and the shape of the landmarks, and on the visibility area of the sensor embedded, the registration maps are computed indicating the sets of robot poses to detect the different landmarks considered in order to reduce the uncertainty on the robot position. Secondly, based on a parametric motion model with uncertain parameters, an high level strategy is provided through a raph optimization. The strategy consists in navigating between the registration maps toreduce each times the uncertainty in position of therobot and finally to guarantee the reachability of agoal area corresponding to the redetection of the target
35
Torres, Filho Ari do Amaral. "Análise da utilização de métodos ágeis no desenvolvimento de ambientes virtuais de aprendizagem: um estudo de caso do Solar 2.0." reponame:Repositório Institucional da UFC, 2014. http://www.repositorio.ufc.br/handle/riufc/13359.
Анотація:
TORRES FILHO, A. A. Análise da utilização de métodos ágeis no desenvolvimento de ambientes virtuais de aprendizagem: um estudo de caso do Solar 2.0. 2014. 158 f. Dissertação (Mestrado em Ciência da Computação) - Centro de Ciências, Universidade Federal do Ceará, Fortaleza, 2014.Submitted by Daniel Eduardo Alencar da Silva (dealencar.silva@gmail.com) on 2015-01-23T20:18:36Z No. of bitstreams: 1 2014_dis_aatfilho.pdf: 5052662 bytes, checksum: bbc494f5731e2ba4a447896641ee5d11 (MD5)
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In the last two decades there has been considerable progress in the use of Information Technologies and Digital Communication in the process of teaching and learning, both in the form of classroom education as distance. In this context, the use of Virtual Learning Environments - software designed to support the courses via the Internet - is growing and access becoming increasingly diverse, ranging from desktop computers to mobile smartphones. Thus, the complexity of creating these environments becomes increasingly technical and requires Software Engineering and Project Management always better to ensure product quality and customer satisfaction generated. Given such a scenario, this paper proposes the use of Agile methodologies in the development and project management of virtual environments as a more interesting way than traditional software delivery based only on product quality, forgetting often , customer satisfaction and motivation of developers. This paper reports the adoption of agile methodologies in the development of the SOLAR AVA 2.0, showing that it is possible to succeed in both the technical level and at the organizational and personally with the adoption of agile practices in the development of AVAs that can be proven through experiments done with the satisfaction surveys with users and project developers.
Nas duas últimas décadas houve um considerável avanço no uso de Tecnologias da Informação e Comunicação Digitais no processo de ensino e aprendizagem, tanto na modalidade de Educação presencial quanto a distância. Neste contexto, o uso de Ambientes Virtuais de Aprendizagem - softwares criados para o suporte a cursos através da Internet - vêm crescendo e seu acesso se tornando cada vez mais diversificado, indo de computadores desktop a celulares smartphones. Desta forma, a complexidade de criação destes ambientes se torna cada vez maior e exige técnicas de Engenharia de Software e Gestão de Projetos cada vez melhores para garantir a qualidade do produto gerado e a satisfação do cliente. Tendo em vista tal cenário, o presente trabalho propõe o uso de Metodologias Ágeis tanto no desenvolvimento quanto na gestão de projetos de ambientes virtuais como uma solução mais interessante que a tradicional forma de criação de softwares baseada somente na qualidade do produto, esquecendo, muitas vezes, a satisfação do cliente e a motivação dos desenvolvedores
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Mathieu, Antoine. "Contribution à la conception et à l'optimisation thermodynamique d'une microcentrale solaire thermo-électrique." Thesis, Université de Lorraine, 2012. http://www.theses.fr/2012LORR0027/document.
Анотація:
En ce début de millénaire 1,4 Milliards d'humains, parmi les plus démunis de la planète, vivent dans des sites isolés et ne bénéficient pas de réseaux de distribution d'énergie. Leur besoin en électricité est modeste, mais important en terme d'usages : accès aux soins médicaux et à l'instruction, communication, développement d'économies locales. C'est face à ce constat que Schneider Electric Industries relève, depuis 2009, le défi de concevoir et réaliser des microcentrales solaires thermodynamiques, concurrentielles à d'autres solutions, pour fournir à ces populations une énergie électrique fiable et respectueuse de l'environnement. Inscrit dans le cadre de ce projet, le présent travail - réalisé en Cifre - est séquencé par l'évolution industrielle du projet. Dans un premier temps, un Etat de l'Art, étendu à une analyse de détail, a contribué à privilégier certains choix technologiques : capteurs solaires à concentration, stockage thermique à chaleur sensible et moteur de Stirling. Dans un second temps, une étude thermodynamique préliminaire a permis d'évaluer le dimensionnement d'éléments clefs du système : champ de captage solaire et stockage thermique. En complément une étude de sensibilité paramétrique du dimensionnement et des performances à divers facteurs de pertes énergétiques a souligné les points durs techniques et participé à l'orientation des travaux de conception. Enfin, l'analyse exergétique de fonctionnement de capteurs solaires et d'un moteur Stirling en régimes dynamiques stationnaires proposent des bases pour l'optimisation de contrôle et commande, visant à accroître les performances énéergétiques du système et favoriser sa viabilité thermoéconomiqueAs a new millenium begins, 1.4 Billion people worldwide earn less than 2 dollars daily and have no access to the power grid. The need of electric power of these people represent small energy amounts but is very important regarding to the usage : acces to healthcare and education, communication, local economic development. In reponse to the situation, since 2009, Schneider Electric Industries takes up the challenge to design and realize micro solar power plants, competitive with other solutions, to supply these people with reliable and environment-friendly electricity. Dealing with this project, this work has been realized under contract, so it follows the development sequence of the industrial project. The first part is a State of the Art of the actual solar thermodynamical technologies. This task is extended to a qualitative evaluation of various technologies, as a contribution to select adapted technologies: concentrating solar thermal receivers, sensible heat thermal storage and Stirling engine. The secon step is a preliminary thermodynamics analysis of the whole system, that allowed to evaluate key features: the size of the solar receivers area, the thermal storage volume, and overall energy performance. This task is streched by a sensitivity analysis of the sizing and performances, according to various energy losses parameters, that shows the technical hard spots of the design. Finally, an exergy-based dynamical analysis of stationary operating solar receivers and Stirling engines leads to a propostion of basis methods and criteria for the optimal control of power, in order to maximize the energy performances of the system and to enhance its competitiveness
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Khan, MD Ershad Ullah. "Renewables Based Polygeneration for Rural Development in Bangladesh." Doctoral thesis, KTH, Kraft- och värmeteknologi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-205556.
Анотація:
Despite the country's rural electrification programme, kerosene is the predominant source for lighting, and unsustainable and polluting woody biomass is virtually the only option available for cooking. The rural population also struggles with unsafe drinking water in terms of widespread arsenic contamination of well water. The present work has taken an integrated approach in an attempt to mitigate problems through small-scale polygeneration, a concept linking renewable energy sources to these energy needs via novel energy conversion systems. Anaerobic digesters (AD) for biogas production are promising in the rural setting, and field surveys have identified problems in the construction, maintenance and operation of existing AD, particularly in overall performance of household digesters. Based on these results, a number of operational and technological improvements are suggested for employing digesters in polygeneration units. This study also examines one approach for small-scale, low cost arsenic removal in groundwater through air gap membrane distillation, a thermally-driven water purification technology. Integration of biogas production with power generation and water purification is an innovative concept that lies at the core of feasibility analyses conducted in this work. One of the case studies presents a new concept for integrated biogas based polygeneration and analyzes the techno-economic performance of the scheme for meeting the demand of electricity, cooking energy and safe drinking water of 30 households in a rural village of Bangladesh. The specific technologies chosen for the key energy conversion steps are as follows: plug-flow digester; internal combustion engine; and membrane distillation. One major concern is local feedstock availability for the digester, since a single feedstock is impractical to serve both cooking, lighting and water purification systems. In this circumstance solar PV could be a potential option for integrated hybrid systems.Bangladesh har varit föremål för en svår energikris (bristande el- och gasnät) de senaste tre decennierna. Landsbygden, som innefattar 75 % av befolkningen, har varit särskilt drabbad. Trots landets elektrifieringsprogram av landsbygden är fotogenlampor den företrädande ljuskällan, medan förorenande och ohållbar träbaserad biomassa är praktiskt taget det enda alternativet för matlagning. Landsbygden kämpar samtidigt mot osäkert dricksvatten, på grund av utbredd arsenikförgiftning av brunnsvatten, med negativa hälsoeffekter som följd. Tillgång till ren energi och säkert dricksvatten är verkliga behov bland de fattiga på landsbygden, för ökad välfärd. Detta arbete antar ett integrerat tillvägagångssätt för att försöka lösa dessa problem genom småskalig polygenerering. Detta koncept länkar samman förnyelsebara energikällor av biomassa och sol med energibehoven, genom nya energiomvandlingssystem. Anaerobiska rötkammare för biogasproduktion är lovande för landsbygdsmiljö, även om det för närvarande råder en betydande klyfta mellan den tekniska och kostandseffektiva potentialen och faktisk implementering på grund av bristande tekniskt kunnande och tillgång på råmaterial, höga installations- och driftkostnader, och begränsade användartillämpningar. Intervjuundersökningar visar på problem i konstruktion, underhåll och drift av befintliga anaerobiska rötkammare. Särskilt den generella prestandan hos hushållsrötkammare identifieras som bristfällig. Utifrån dessa resultat föreslås en rad drift- och teknikförbättringar för att utnyttja rötkammare i polygenereringssystem. Denna studie undersöker även en metod för småskalig och kostnadseffektiv arsenikrening av grundvatten genom membrandestillation med luftspalt (Air Gap Membrane Distillation, AGMD), vilket är en termiskt driven vattenreningsteknik. Resultat från en experimentell undersökning visar att den undersökta AGMD-prototypen är kapabel att uppnå utmärkt separationseffektivitet med hänsyn till arsenikrening. Parametriska studier med fokus på varierande kylvattentemperatur illustrerar möjligheten att integrera AGMD-teknik i diverse termiska system. Integrering av biogasproduktion med kraftproduktion och vattenrening är ett innovativt koncept som utgör kärnan av förstudierna utförda i detta arbete. En av studierna visar ett nytt koncept för biogasbaserad polygenerering och analyserar den techno-ekonomiska prestandan av metoden för att möta efterfrågan av elektricitet, matlagningsvärme och säkert dricksvatten för 30 hushåll i en Bangladeshisk by på landsbygden. De specifika tekniker som valts för energiomvandlingsstegen är följande: plugg-flödesrötkammare, förbränningsmotor och en AGMD-enhet. Termodynamisk utvärdering inklusive mass- och energibalans av systemet undersöktes tillsammans med produktionskostnaden för elektricitet, matlagningsgas, och säkert dricksvatten. Även återbetalningsperiod och internräntan undersöktes. För att bemöta energi- och arsenikproblemen i Bangladesh, indikerar resultaten att detta polygenereringssystem är mycket mer konkurrenskraftigt och lovande (med avseende på produktionskostnaderna) jämfört med andra tillgängliga tekniker. Ett viktigt problem för rötkammaren är tillgången till lokalt råmaterial, eftersom en ensam källa till råmaterial är opraktiskt för att tillgodose efterfrågan från både matlagning, belysning och vattenrening. I detta fall kan solceller vara ett potentiellt alternativ för integrerade hybridsystem. Teknisk värdering och optimering har genomförts för elektricitet med verktyget HOMER (Hybrid Optimization of Multiple Energy Resources), för ett polygenereringssystem beläget i byn Panipara i Faridpur. Resultaten visar att systement kan tillgodoses det dagliga elektricitetsbehovet och samtidigt producera 0.4 m3 matlagningsbränsle och 2-3 L/person rent dricksvatten. Kostnadsuppskattningar visar att denna metod är högst gynnsam jämfört med andra förnyelsebara alternativ (t ex vind-, vatten-, biobränslebaserad- eller geotermisk energi).
QC 20170419
SIDA – the Swedish International Development Cooperation Agency, Department for Research Cooperation, SAREC- project no. SWE-2011-135
STEM-Fjärrsyn project 2014
38
Harant, Miroslav. "Využití solární energie pro elektromobilitu." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2019. http://www.nusl.cz/ntk/nusl-413046.
Анотація:
The thesis deals with the use of solar energy for electromobility. First, the potential of electromobility on the current market is theoretically discussed. This issue includes mainly the producers of electrically powered vehicles, the issue of electric energy storage and the real applications of fast charging and photovoltaic charging stations. In the next part, electric cars are analyzed, which use solar energy for their function and their efficiency is compared with the effiency of combustion engines. The main part of this thesis is the design of photovoltaic charging station for electric vehicles. The final part deals with the economic evaluation of the proposed charging station.
39
Harant, Miroslav. "Využití solární energie pro elektromobilitu." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2020. http://www.nusl.cz/ntk/nusl-413232.
Анотація:
The thesis deals with the use of solar energy for electromobility. First, the potential of electromobility on the current market is theoretically discussed. This issue includes mainly the producers of electrically powered vehicles, the issue of electric energy storage and the real applications of fast charging and photovoltaic charging stations. The second part of the diploma thesis deals with the measurement of electric car consumption and the evaluation of measurement results. In the next part, electric cars are analyzed, which use solar energy for their function and their efficiency is compared with the effiency of combustion engines. The main part of this thesis is the design of photovoltaic charging station for electric vehicles. The final part deals with the economic evaluation of the proposed charging station.
40
Fula, Rojas Manuel Alejandro. "Modélisation thermique, thermodynamique et expérimentation d'un moteur ericsson a air chaud a cycle de joule." Thesis, Pau, 2015. http://www.theses.fr/2015PAUU3055/document.
Анотація:
Avec l'épuisement des ressources naturelles, notamment les sources d’énergies fossiles, les énergies renouvelables sont à nouveau considérées comme une alternative réelle pour la transition énergétique des pays industrialisés.Les moteurs à apport de chaleur externe comme le Stirling et son « cousin » le moteur Ericsson peuvent valoriser de multiples sources -renouvelables ou non- d'énergie thermique. Le moteur Ericsson est ainsi particulièrement bien adapté pour la conversion de l’énergie solaire ou de la biomasse en électricité dans des applications de microcogénération.Cette thèse s’inscrit dans la continuation des travaux théoriques et expérimentaux sur le moteur Ericsson réalisés au LaTEP de l'Université de Pau et des Pays de l'Adour. Dans ce travail, nous nous sommes principalement intéressés auxtransferts thermiques entre le fluide de travail et les parois des cylindres de compression et de détente du moteur. Un premier modèle, global, a permis de déterminer dans quelles conditions ces transferts thermiques peuvent améliorer les performances du système énergétique considéré. Un second modèle, ‘intracycle’, a permis d’évaluer les transfertsthermiques instantanés dans les cylindres à partir des corrélations habituellement utilisées dans les moteurs à combustion interne. Le prototype de moteur Ericsson a alors été équipé de différents capteurs de pression et de températures, ces derniers étant constitués de micro-thermocouples. Les relevés de température instantanée dans lecylindre de compression sont présentés commentés et comparés aux résultats obtenus par le modèle « intracycle »With exhaustion of natural resources, in particular the fossil energy sources, renewable energies are again regarded as a real alternative for the needed energy transition of the industrialized countries. The "hot air engines" like the Stirling engine and his “cousin” the Ericsson engine, can use multiple thermal sources - renewable or not -. The Ericsson engine is thus particularly well adapted for solar or biomass energy conversion in electricity or for microcogeneration purposes. This thesis is a continuation of the theoretical and experimental work on the Ericsson engine realized in the LaTEP of theUniversity of Pau (France). In this work, we are mainly interested in the - in-cylinder - heat transfer between the working gas and the walls of the compression and expansion cylinders of the Ericsson engine. A first original model made possible to determine under which conditions these heat transfers can improve the performances of the energy system considered. A second model, “intracycle”, allowed to evaluate the instantaneous heat transfers in the cylinders starting from the correlations usually used in the internal combustion engines, reciprocating compressors and pneumatic springs. The Ericsson prototype was then equipped with various pressure and temperature gauges, the latter consisting of K-type microthermocouples of 25 and 12,5μm wires. The results of instantaneous temperature measurements in the compression cylinder are presented, commented and compared with the results obtained by the “intracycle” model
41
Rousselle, Denis. "Classification d’objets au moyen de machines à vecteurs supports dans les images de sonar de haute résolution du fond marin." Thesis, Rouen, INSA, 2016. http://www.theses.fr/2016ISAM0020.
Анотація:
Cette thèse a pour objectif d'améliorer la classification d'objets sous-marins dans des images sonar haute résolution. En particulier, il s'agit de distinguer les mines des objets inoffensifs parmi une collection d'objets ressemblant à des mines. Nos recherches ont été dirigées par deux contraintes classiques en guerre de la mine : d'une part, le manque de données et d'autre part, le besoin de lisibilité des décisions. Nous avons donc constitué une base de données la plus représentative possible et simulé des objets dans le but de la compléter. Le manque d'exemples nous a mené à utiliser une représentation compacte, issue de la reconnaissance de visages : les Structural Binary Gradient Patterns (SBGP). Dans la même optique, nous avons dérivé une méthode d'adaptation de domaine semi-supervisée, basée sur le transport optimal, qui peut être facilement interprétable. Enfin, nous avons développé un nouvel algorithme de classification : les Ensemble of Exemplar-Maximum Excluding Ball (EE-MEB) qui sont à la fois adaptés à des petits jeux de données mais dont la décision est également aisément analysableThis thesis aims to improve the classification of underwater objects in high resolution sonar images. Especially, we seek to make the distinction between mines and harmless objects from a collection of mine-like objects. Our research was led by two classical constraints of the mine warfare : firstly, the lack of data and secondly, the need for readability of the classification. In this context, we built a database as much representative as possible and simulated objects in order to complete it. The lack of examples led us to use a compact representation, originally used by the face recognition community : the Structural Binary Gradient Patterns (SBGP). To the same end, we derived a method of semi-supervised domain adaptation, based on optimal transport, that can be easily interpreted. Finally, we developed a new classification algorithm : the Ensemble of Exemplar-Maximum Excluding Ball (EE-MEB) which is suitable for small datasets and with an easily interpretable decision function
42
Kmeť, Jozef. "Problematika snižování tepelné odrazivosti zrcadel solární elektrárny se Stirlingovým motorem." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-231827.
Анотація:
This thesis describes a concentrating solar power using a Stirling engine. The problems encountered during construction and operation. I focus mainly on problems derating dusting and icing. The second part of this work is the experimental design of the stand with long-term measurement of dusting depending on the reflectivity of mirrors and their degradation under various conditions. First measurement is stated and estimation of long-term results.
43
Bouvier, Jean-Louis. "Étude expérimentale d'une installation de micro-cogénération solaire couplant un concentrateur cylindro-parabolique et un moteur à cycle de Hirn." Thesis, La Rochelle, 2014. http://www.theses.fr/2014LAROS031/document.
Анотація:
L’objectif de cette thèse est d’étudier expérimentalement les performances énergétiques d'une installation de micro-cogénération solaire. Le prototype réalisé est constitué d'un concentrateur cylindro-parabolique associé à un moteur à vapeur fonctionnant suivant un cycle de Hirn (Rankine avec surchauffe). Les originalités de ce projet sont l’utilisation de l’énergie solaire, renouvelable et inépuisable mais intermittente, la génération directe de vapeur au sein d'un concentrateur de taille réduite (46,5 m²), le système de suivi solaire sur deux axes et le couplage à un moteur à piston non lubrifié. La première partie de l'étude porte sur le concentrateur seul. Son fonctionnement est étudié sur deux journées types (ensoleillée et nuageuse) et son rendement thermique est évalué. La dynamique du système est également abordée notamment par l'étude de sa réponse à des perturbations. Une régulation de type boucle ouverte a été mise en place et validée. La seconde partie concerne la caractérisation du moteur seul. Des essais ont été menés avec une puissance de source chaude stable puis variable. À partir des résultats obtenus, un modèle empirique est développé, puis exploité dans le cadre d'une étude paramétrique du moteur. Cette étude montre l'influence importante du ratio de pression et de la vitesse de rotation sur le rendement. Dans la dernière partie, les performances globales (rendement, puissances électrique et thermique produites) du micro-cogénérateur sont évaluées. Des essais à pression et à vitesse régulées sont présentés. A partir de cartographies de fonctionnement réalisées à l’aide d’un modèle empirique, une régulation basée sur l'utilisation d'un by-pass est alors mise en place, puis testéeThe objective of this thesis is the experimental study of the energy performances of a micro combined solar heat and power (micro-CHP) unit. The prototype is composed of a solar parabolic trough collector coupled to a Hirn (superheated Rankine) cycle engine. The originalities of this project are the use of solar energy which is renewable and inexhaustible but intermittent, the direct steam generation with a reduced size parabolic trough collector (46.5 m²), the two axis tracking system and the coupling with an oil-free reciprocating steam engine. The first part of this study is focussed on the solar collector. Thermal performances under sunny and cloudy conditions are presented and the thermal efficiency is evaluated. The system dynamic is also investigated through the characterization of the inertia as well as a study of its response to perturbations. Then a control strategy is set up and validated. The second part deals with the characterization of the engine. Tests have been performed with a stable and variable heat source power. From these tests, an empirical model has been developed and used in a parametrical study. This study shows the significant influence of the pressure ratio and of the rotational speed on the efficiency of the engine. In the last part, global performances (efficiency, output thermal and electrical powers) of the entire micro-CHP unit are evaluated. Tests with controlled pressure and speed are presented. From operating maps established from an empirical model, a control strategy based on the use of a by-pass is set up and tested
44
Chi-Cho, Chih-Ming, and 紀卓志明. "Generate Electricity from solar powered Stirling Engines." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/86424902155917892258.
Анотація:
碩士萬能科技大學
工程科技研究所
97
A small Stirling engine generator driven by solar energy comprises a disk to concentrate sunlight, a device to track the sun, a Stirling engine and a generator. A program, written in Mat lab and Lab View and based on the Schmidt model, was used to analyze the performance of a Stirling engine and to evaluate the factors critical to its performance. The results of this theoretical simulation are as follows. The work done per cycle by a Stirling engine increases with increasing difference of temperature between the hot and cold ends of that engine. Decreasing the volume so called dead inside the Stirling engine increases the work done by the Stirling engine. For a phase difference between the reciprocating motion of the piston and that of the displacer in a range 85o -- 95o, the output of the Stirling engine varies insignificantly. To enhance the performance of the Stirling engine, the ratio between the volume swept by the piston and the volume of the displacer must be adequate. To maximize the temperature of the hot end of the Stirling engine, we designed and fabricated a concentrating disk, which comprises about 500 flat mirrors, to focus the sunlight to a point. Because the performance of a Stirling engine is insensitive to the phase difference between the reciprocating motions of the piston and of the displacer, we designed and applied a L-shaped linkage to simplify the structure of a Stirling engine. Several new designs of a Stirling engine are proposed and tested to maintain the temperature difference between the hot and cold ends of the chamber. We made and tested a solar-powered Stirling engine generator that produces electricity; this work proves the feasibility of a tiny Stirling engine generator being driven by solar energy.
45
Pudney, Peter. "Optimal energy management for solar-powered cars." 2000. http://arrow.unisa.edu.au:8081/1959.8/24969.
Анотація:
Solar powered cars may never be practical. Nevertheless, in the 1996 World Solar Challenge the Honda Dream carried two people 3000km across Australia at an average speed of 90km/h, powered only by sunlight. You clearly don?t need a 2500kg machine powered by polluting fuels to get you to work and back each day. The Australian Aurora 101 solar powered car requires less than 2000W of power to travel at 100km/h. To achieve such high performance the car has high aerodynamic efficiency, motor efficiency greater than 98%, low rolling resistance tyres, and weighs less than 280kg with the driver in it. The energy used to propel the car is generated by high-efficiency photovoltaic cells Another key to achieving high performance is efficient energy management. The car has a small battery that can store enough energy to drive the car about 250km at 100km/h. Energy stored in the battery can be used when extra power is required for climbing hills or for driving under clouds. More importantly, energy stored while the car is not racing can be used to increase the average speed of the car. How should the battery be used? The motivation for this problem was to develop an energy management strategy for the Aurora solar racing team to use in the World Solar Challenge, a triennial race across Australia from Darwin to Adelaide. The real problem? with weather prediction, detailed models of the car and numerous race constraints?is intractable. But by studying several simplified problems it is possible to discover simple rules for an efficient energy management strategy. The simplest problem is to find a strategy that minimises the energy required to drive a car with a perfectly efficient battery and a constant drive efficiency. The optimal strategy is to drive at a constant speed. This is just the beginning of the solar car problem, however. More general problems, with more general models for the battery, drive system and solar power, can be formulated as optimal control problems, where the control is (usually) the flow of power from or to the battery. By forming a Hamiltonian function we can use Pontryagin?s Maximum Principle to derive necessary conditions for an optimal strategy. We then use these conditions to construct an optimal strategy. The strategies for the various simplified problems are similar: ? On a level road, with solar power a known function of time, and with a perfectly efficient drive system and battery, the optimal strategy has three driving modes: maximum power, speed holding, and maximum regenerative braking. ? If the perfectly efficient battery is replaced by a battery with constant energy efficiency then the single holding speed is replaced by two critical speeds. The lower speed is held when solar power is low, and the upper speed is held when solar power is high. The battery discharges at the lower speed and charges at the higher speed. The difference between the upper and lower critical speeds is about 10km/h. There are precise conditions for switching from one mode to another, but small switching errors do not have a significant effect on the journey. ? If we now change from a level road to an undulating road, the optimal strategy still has two critical speeds. With hills, however, the conditions for switching between driving modes are more complex. Steep gradients must be anticipated. For steep inclines the control should be switched to power before the incline so that speed increases before the incline and drops while the car is on the incline. Similarly, for steep declines the speed of the car should be allowed to drop before the decline and increase on the decline. ? With more realistic battery models the optimal control is continuous rather than discrete. The optimal strategy is found by following an optimal trajectory in the phase space of the state and adjoint equations. This optimal trajectory is very close to a critical point of the phase space for most of the journey. Speed increases slightly with solar power. As before, the optimal speed lies within a narrow range for most of the journey. ? Power losses in the drive system affect the initial power phase, the final regenerative braking phase, and the speed profile over hills. The optimal speed still lies within a narrow range for most of the journey. ? With spatial variations in solar power it is possible to vary the speed of the car in such a way that the extra energy collected more than compensates for the extra energy used. Speed should be increased under clouds, and decreased in bright sunlight. The benefits of ?sun-chasing? are small, however. ? Solar power is not known in advance. By modelling solar power as a Markov process we can use dynamic programming to determine the target distance for each remaining day of the race. Alternatively, we can calculate the probability of completing the race at any given speed. These principles of efficient control have been used successfully since 1993 to develop practical strategy calculations for the Aurora solar racing team, winner of the 1999 World Solar Challenge.Thesis (PhD)--University of South Australia, 2000
46
Gohary, Mohamed Morsy Abdel Meguid Salama el [Verfasser]. "Diesel engines and solar energy for electric and cooling applications / von Mohamed Morsy Abdel Meguid Salama el Gohary." 2004. http://d-nb.info/973168242/34.
47
Tsung, Yueh Tsai, and 蔡宗岳. "Heat pipe-type Stirling engine solar." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/11976965447455688477.
Анотація:
碩士萬能科技大學
工程科技研究所
99
In this paper, we develop a Fresnel lens focusing sunlight, heating the heat pipe, the use of heat pipe working fluid in the phase change occurs, the temperature the same way, through the heat pipe heat transfer to the Stirling solar thermal heating at, The heating temperature difference Stirling engine, Stirling engine to operate, thus promoting hair dryer power, this low temperature difference Stirling engine can be used for geothermal power generation. Heat pipe-type Stirling engine solar power technology can be further combined with the building, and then from the building surfaces absorb a lot of heat, to promote the Stirling engine, on the other so that the temperature inside the building, declined in summer air-conditioning usage to reduce energy consumption. This study is the first Taiwan first type Stirling engine heat pipe solar system, its main structure is divided into two parts: ○1 using heat pipe system to absorb sunlight heat, sunlight, heat and then transfer to the Stirling engine to heat the heating side, the other using a simple Fresnel lens to increase the heat pipe system, heat-absorbing performance. ○2 sing low temperature difference Stirling engine, low temperature difference Stirling engine as part of the high temperature low temperature, so the design it has great flexibility. This research was supported by the main conclusion is that, ○1 in the heat pipe working fluid, will have to use abnormal working fluid phase is a better choice. ○2 resnel lens can be further improved to reduce the Fresnel lens with diffuse diffuse refraction phenomena, the focus of the situation better, the other because the Fresnel lens is very light, so if you want to catch on with the system, then can also simplify the Fresnel lens on the way to recover. ○3 Stirling engine, we made the following improvements, such as gas transfer many of the carcass in the drill hole, to reduce the working fluid resistance caused by friction, but also activities such as all parts are perpendicular to the ground as possible, so that the weight of their own generated by friction can be minimized, and then followed us to increase the radius of the piston, so that the temperature is not the case, to make Stirling engine running, while we use the appropriate link structure to reduce friction. In this study, design, production, testing this type of Stirling engine, a heat pipe solar system, given the power to make it successful, confirms this idea is a potential for development.
48
Chang, Yin-Yu, and 張吟瑜. "CFD simulation of a solar Stirling engine." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/snwcq4.
Анотація:
碩士淡江大學
化學工程與材料工程學系碩士班
102
In a solar desalination project, an alpha type solar Stirling engine is developed from a commercial diesel engine by adding heater, cooler and regenerator as well as modifying crankshaft system. In this thesis, the 3-D Computational Fluid Dynamic (CFD) simulation of a single axi-symmetric channel of the engine is presented. The FLUENT software and the RNG k-ε turbulence model are employed for the simulation. Special treatments are adopted for the simulation, including the piston is defined as a dynamic boundary, the cylinder spaces use dynamic mesh and non-equilibrium model is used for the regenerator, where the screen solid and fluid are different in temperature. The simulation results reveal that compared to the base design, the optimal design releases less heat from the cooler and has higher efficiencies of engine and regenerator. The CFD simulation results are utilized to develop correlations of friction factor and heat transfer coefficient for each heat exchanger. These correlations are valuable design tools for Stirling engines.
49
Chou, Ying-Hsiu, and 周盈秀. "Simulation study of a solar concentrator operated Stirling engine." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/n9ftv2.
Анотація:
碩士淡江大學
化學工程與材料工程學系碩士班
102
This study has established a second order mathematical model of alpha type solar powered Stirling engine, and solar collectors of design. The study simulates a diesel engine with nitrogen as the working fluid, basic design analysis and optimal design, and the decision the Stirling engine supply the desalination membrane distillation system energy. The simulation of the optimal design case reveals the cyclic operating conditions of the working gas and the solid temperatures. For the gas, the pressure ranged 0.45-3.1 MPa, the maximum pressure difference in the engine is about 0.7 MPa and the temperature ranged 282-709 K. For the metal in the regenerator, the temperature distribution is linear and the effectiveness of the regenerator is 83.87%. The power output from the engine is 9.85 kW and the thermal efficiency is 33.85%. Rotational frequency is 852 rpm. Solar collector receives radiation area is approximately 32.4 m2. When the regenerator heat transfer coefficient using Kelly and McLand (2007) correlation in high radiation intensity 830 W/m2 and the total mass of the working fluid of the engine are 18.16,27.26 and 36.32 g, engine output power are 7.89,8.42 and 8.4 kW. The radiation intensity and the total mass of 670 W/m2, respectively 27.26 and 36.32 g, engine output power are 7.37 and 7.4 kW. If regenerator heat transfer coefficient using Gedeon and Wood (1996) the correlation at high radiation intensity and total mass are 18.16,27.26 and 36.32 g, the engine output power, respectively 7.88,8.22 and 8.21 kW. Under the radiation intensity, and the total mass are 27.26 and 36.32 g, engine output power are 7.2 and 7.24 kW. In the low radiation intensity 560 W/m2, the energy is too low to drive the engine rotation.
50
Chia-EnHo and 何佳恩. "Performance analysis and optimization of solar energy Stirling engine with thermal electrical device." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/26701168913738874394.